Build a 150mm Offset Binoscope

thingiverse

This project is about building a super lightweight 150mm Offset Binoscope. It's called an "Offset" binoscope because its two 6" F5 Newtonian reflectors are offset by 46mm, which allows the eyepieces to be angled at approximately 45 degrees relative to the long axis of the binoscope. This feature provides a much more comfortable viewing angle for the observer, especially when observing near the zenith. Ideally, the mount can be adjusted in height so that the observer stands straight upright while observing the zenith and their eyes are level with the eyepieces. It then only requires a slight tilt of the head to observe comfortably through both eyepieces. Another significant advantage of this type of rectangular construction for the binoscope is that its two Newtonian reflectors are inherently co-collimated by the compact combined assembly using precisely printed parts and aluminum angle struts. The classic approach of independent Newtonian reflectors positioned on either side of the head, where tertiary mirrors are used, demands much more accuracy and robustness from the mechanical structure. As will be explained later, it's crucial to finally glue black ABS plastic sheets (.062 inch thick, available through Amazon) to the sides of the frame to create a very strong and stable assembly as well as blocking stray light. Binoscopes can never be too rigid since even the slightest free play anywhere in the frame or mirror assemblies will lead to loss of collimation as the binoscope is moved around the sky. It's a good practice to glue most of the 3D printed parts to the aluminum frame once everything works. Only the adjustable IPD top telescope focuser should not be glued. I use Devcon Plastic Welder, two-part epoxy, and silicon RTV to glue PLA or PETG parts to the aluminum frame.